how can I get my data usage history for past billing periods

I have a plan that I feel is basically enough data for my use, but we just upgraded our directv and would like to use my internet for on demand movies, and my grandkids games. I'm disabled so I am guilty of not checking my data usage, but Ii wanted to compare my data usage before I connected directv on Dec 5, 2017 and what the data usage is since Dec 5, 2017 so I can see if I want to upgrade to an unlimited plan. How do I get that? Thanks!!

This is not good customer service and just plain not the right thing to do. I can go back and find my water usage, electric usage but not my data usage? I know you have records of usage, you are in business to make money and would not be able to manage your business if you did not have this information. We paid for it and SHOULD be able to have access to OUR information.